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A lot of times I need a circuit like below. Namely, a logic level signal should set a higher voltage (e.g. 12 V) and higher current (few 100 mA, but not Amps) push-pull stage to a hi/lo state at potential frequencies up to maybe 1 MHz. Building this discretely has some pitfalls, e.g. uncertain pull-up time causing shootthrough and EMC trouble. So I believe there are ICs for this, but I can't seem to find anything.

The closest I found are single low-side gate drivers, but these typically aren't rated for continuous current output and hard commutation. They also often seem to be realized with BJTs lacking the reverse current capability of MOSFETs that is needed for inductive loads.

Motor drivers on the other hand don't seem to be available as half-bridges but only as full-bridges.

schematic

simulate this circuit – Schematic created using CircuitLab

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    \$\begingroup\$ Level shifter or level translator but these usually can't deliver much power. The common way is to combine a "Half bridge" gate driver with external MOSFETs. That can be NMOS + PMOS or 2 x NMOS (and a "bootstrap" circuit to raise the voltage). You can use only half of a "full bridge" (motor) driver as a half-bridge. \$\endgroup\$ Oct 15, 2021 at 21:15
  • \$\begingroup\$ @Bimpelrekkie Thanks, I was afraid that this is indeed so. While very flexible and good for really high powers, a half-bridge driver + 2 MOSFETs seems a bit overkill for the range of say 0.1 W - 10 W. And thanks for the half-motor-driver suggestion. Awkward, too, but at least a single component \$\endgroup\$
    – tobalt
    Oct 15, 2021 at 21:23
  • \$\begingroup\$ "Motor drivers on the other hand don't seem to be available as half-bridges but only as full-bridges." Half bridges are certainly available: digikey.com/short/945pjq55 \$\endgroup\$ Oct 15, 2021 at 21:41
  • \$\begingroup\$ @DavideAndrea there are always (?) at least 2 half-bridges. As Bimpelrekkie says I could just not use one, but that seems a little awkward. \$\endgroup\$
    – tobalt
    Oct 15, 2021 at 21:52
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    \$\begingroup\$ @tobalt What is a UC2950T? It's bipolar, not FET. But otherwise is a single half-bridge, yes? \$\endgroup\$
    – jonk
    Oct 15, 2021 at 22:54

2 Answers 2

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You won't find your topology in an IC for high power because of the lack of protection for shoot thru. This is how CMOS Logic output stages look but by design the RdsOn increases with higher Vdd ratings because the RdsOn naturally decreases with higher voltage. So to reduce the concurrent driver power, the RdsOn must be high by design.

If you recall, the CD4xxx family is rated for 16~18V and the RdsOn is 1kohm at 5V then I recall, 300 Ohms at 12V. So I don't see much practical use for high voltage & high current as it is imposible to not have both drivers on at the same time.

Half-Bridge IC's use special deadtime circuit to prevent simultaneous on condition for the complementary shared Drain outputs and the push-pull complementary half-bridge types.

In short, this topology of a low side drain with pullup to drive two complmentary common source outputs is not feasible where Vdd is > 3x Vgs(th) with an RdsOn in the range of 1 ohm due to self-heating.

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  • \$\begingroup\$ Hmm, but gate driver ICs seem to use exactly this arragement of PMOS and NMOS, e.g.: datasheet.octopart.com/… Typical gate driver ICs also use 12 V or more and have \$R_{on}\$ on the order of 1-3 Ohm. So it seems that shootthrough is no problem for gate drive ICs ? \$\endgroup\$
    – tobalt
    Oct 18, 2021 at 11:16
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So I believe there are ICs for this, but I can't seem to find anything.

There are a lot of new applications emerging for driving MOSFETs with optical isolation and high speed. One of these might suit your needs. In particular, I'm thinking of ON semiconductors FOD8343. Of course, you don't need optical isolation so you gain no benefit from it but, it comes nevertheless. It can handle 100 mA loads all day and has a maximum propagation delay of 210 ns. It's rated for supplies between 10 volts to 30 volts and drops typically 0.1 volts when driving a 100 mA load.

So, this may not be ideal for you but, it gives you another category avenue to explore: -

High Speed Gate Drive Optocoupler

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  • \$\begingroup\$ thanks for the category name.. Ive come to the conclusion that the term 'Half-Bridge driver' seems to be used interchangeably for both integrated half bridges (with power MOSFETs) as well as for half-bridge gate drivers.. \$\endgroup\$
    – tobalt
    Oct 16, 2021 at 13:10

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